The present invention relates to a sensor for use in operating mobile farming machineries and, more particularly, a sensor adapted to control the operation of the farming machineries by means of an electric signal obtained through a photoelectric conversion of an optical image of a paddy field.
In automatic operation of a mobile farming machine, it is often required to control the machine to make it run along a predetermined path of work.
Various types of sensors have been proposed and used for this automatic control of the machine. Among these sensors, a sensor incorporating sensing lever and a switch combined with the latter is most popular. However, this type of sensor requires objects suitably disposed in the paddy field so as to be contacted by the sensing lever, as well as various preparatory works. At the same time, this mechanical type of sensor is considerably large and occupies a large installation space on the machine, so that it can be attached only to selected portions of the machine. In addition, the mechanical sensor is apt to be broken by an accidental application of external force. Furthermore, the contacts of the electric switch tends to be deteriorated, due to the atmosphere of the working environment.